.3 
 
AN INVESTIGATION ON THE PRODUCTION OF LEAD 
 ARSENATE BY ELECTROLYTIC METHOD 
 
 BY 
 
 ARATA LEO NITTA 
 
 THESIS 
 
 FOR THE 
 
 DEGREE OF BACHELOR OF SCIENCE 
 IN CHEMISTRY 
 
 COLLEGE OF LIBERAL ARTS AND SCIENCES 
 UNIVERSITY OF ILLINOIS 
 1922 
 
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UNIVERSITY OF ILLINOIS 
 
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 191 
 
 THIS IS TO CERTIFY THAT THE THESIS PREPARED UNDER MY SUPERVISION BY 
 
 ENTITLED. 
 
 IS APPROVED BY ME AS FULFILLING THIS PART OF THE REQUIREMENTS FOR THE 
 DEGREE OF 
 
 Instructor in Charge 
 
 Approved : 
 
 
 HEAD OF DEPARTMENT OF 
 

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ACniOwLEIiG-LIEIIT 
 
 To Professor I'utnum, under Yvhose direction this 
 investigation 'jvas carried out, the writer wishes to 
 express his gratitude for many valuable suggestions 
 and kind guidance. Thanks are also due hr. hiet- 
 ricson , T;ho by furnishing necessary apparatus, has 
 made the laboratory work possible. 
 
Digitized by the Internet Archive 
 in 2015 
 
 https://archive.org/details/investigationonpOOnitt 
 
liJTROi^UCTIOK. 
 
 The electrolytic process is a recent advancement on 
 the manufacture of various pigments and some chemicals, 
 x-ef erences : - 
 
 ’'The i.i£,nufac tur e of Chemicals by Electrolysis" by x-.. 
 y • Hale . 
 
 "Electrolytic production of Yvhite lead, cadmuim yel- 
 lo 7 /, of murcury vermillion, of ^icheele's green, and of 
 Eerlin blue," in “x^perimentalElecti ochemistry" by rxop- 
 kins , pp. I£E- i32. 
 
 -several patents have been grantedon the manufacture 
 
 of Yvhite leadby electrolysis. 
 
 u . S . 644 , 7 7 6 1 19 uO ; by huckOYv . 
 
 "fin Electrolytic xrocess for xvxanufacture of .-'hite 
 xjead" , by .iilliams, -Rm. 9hem. xjOc . ( 189 5 ) p.8a5. 
 
 Y "xrocess of -i.ianuf. -ixead salts b^ electrolysis 
 U.S. 67 5, 455U90rjby d. B. Tibbits. 
 
 "liethod of x.xanuf . of eeed salts by electrolysis 
 U. X.. 1? 306,948 by e. narringt oni 1919 i . 
 
 "..hite x.eo.d by xjlectr olysis " by n.?x . Bro'wn. 
 u. e. 496,r09 and. 56a, 555. 
 
 ^^nd several others. 
 
 
- 2 - 
 
 It is claimed that the electrolytic production of vihite 
 lead has a great advantages over the old proeer:ses of nutch, 
 or -rench, o_ the '-^arterS. 
 
 V/hy then the similar process can not be applied on the 
 production of lead arsenater 
 
 The inve^. tigation involves technical process based 
 upon the chemical theories and the vvhole success moreover 
 depends upon the economical standpoint o_ the manufacturing . 
 in attacking tho problem it is veil, hovever, at the first 
 hand to consider the successful production o: lead arsenate 
 vithout considering all the economical factors involved. 
 
 After finding the favorable cojnditions of itsmanufacture 
 the economical features, such as the cost of rav materials, 
 amount of energy to be consumed, the cost oi labor for the 
 production, and the conditions should be considered, 
 
 I'he sphere of the vork is vide and it requires a 
 profound knovlvdge of electrochemistry coupled with an 
 ability in doing researches. 
 
 my work is simply a preliminary survey on the sub- 
 ject ‘and 1 leave this work undone to a promising electro- 
 chem.ist, r;ho may happen to bump on this stumbling block 
 in some future days, 
 
 i'he main influencing conditions on the process to 
 be investigate are the f ollowings : - 
 
 1. I'lature of the electrolyte, 
 
 2. concentration of electrolyte u.:ed. 
 
 5. xemperature influences under which tfie. process 
 
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-;d- 
 
 is worked. 
 
 4. .suitable materials for the electrode. 
 
 5. >^iiitable electrode area and current density. 
 
 6. iniuences of electrode portentials. 
 
 7... Specific gravity of electrodes before and after 
 the electrolysis. 
 
 8. x^ature oi the precipitates obtained. 
 
 9. Economical investigation on the process, etc. 
 
j.iiix C2'TiinCiij Uii’ i.i'i kjjLjC • 
 
 Cult ivc^tc d plL^nts are blvvays more susceptible to dis- 
 ec.se and are attacked' by incects than are the Vv'ild plants. 
 The more highly developed become our a^ricultuaip- oduc ts 
 the more care i.-. necessary to protect them from agencies 
 which will hinder their gro\;th. rhi.. ic the reason tha 
 
 the manufacture of agricultual insecticides and fungicides 
 has become the highly important industry. 
 
 Classes ox .iii'd ihox.Ci]iOlJJij 
 
 There s-ire two classes of insects; one ii. chewing 
 insectsand the other is sucking in..ects. ^hewing 
 
 insects bite or chew the foliage or fruit until they act- 
 ually . destroy the plants. tiaterpillers o;. all kinds, 
 beetles and cut worms are this type. These che'wing 
 
 inoects are killed most easily by Lpraying the poison, 
 u'.ually ar. enic compounds, oyer the plants. x-or 
 
 this purpose lead arsenate, and recently calcium ar., enate 
 are most successfully used. 
 
 TO the latter class of insects belong various mites 
 or scales and plant, lice. X’or /insecticide ox this 
 
 class, it ic necessary to use .:ome materials which v.ill 
 killby coming in contactwith the body of the insect, 
 hicotine sulfate , lime sullur 
 
 and some othbrs are used 
 
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Kixli Oxu^ u li'. 01:' Ut-'xj Oi}' J.is Kj vJ ’J?X O -LLi Ij1\ X 'i'1-.lJ »j Xii. i.'i-ii-' * 
 
 X'he insecticide business got its reaX start when 
 'the ooXoro-do potato beetXe took up its ^journey eastward 
 and began infesting the potato fieXdin the eastern part 
 of the country. J-t i found that aceto- arsensfce of 
 
 cop>per or -faris green, whiich is used as a green pigment, 
 couXd be used on tlie potato vines with good effect. 
 
 • 9 
 
 Oonsiderabie success Y/as met with and befor Xong tb.e use 
 of arsenic compounds in paint became unpopuXar and Y^arious 
 chrome greens took tlieir place with the resuXtt that for 
 many years tlie production of raris green has been practical 
 ly for . insecticide use only. s^radually tliis ..was 
 
 tried for another plants , but the soluble portion of 
 tXie arsenic was absorbed by tlie plants and burning effect 
 on plant v.'as marked. 
 
 At tlie- time of the gipsy moth outbreak in 
 iviassachusetts , it Yvas suggested that arsenate of lead 
 contained very little v^ater solubleax'oenic , might be 
 used to advantage. it was tried out and , found 
 
 suitable in many Yvays for this purj^ose. hesiaesb 
 being insoluble and tb.us practically harmless to very 
 tender foliage, it also had another a'dvantage over 
 la.ris green in that, in its linely devided form after 
 drying from the sprs.y soj.ution, it adheres to the leaves 
 and was not readily washed of.J by the, rain, ^irsenate 
 
 of lead, hence, grew in popularity. 
 
 j-t could be 
 
 usea 
 
- 6 - 
 
 on neary all foliages without donger of burning and v;ould 
 cling to the vines or to the foriage through several rain 
 storms, and has a high killingn power. 
 
 bTjiUiii Ci' i.uh'i Lh ^j.C TUxLij Gi 
 
 ari~enaoe , useu up do -lGOG , was pi'epareo. at 
 home by each user without much or any chemical knowledge 
 mostly by mixing the solutions of sodium arsenate and lead 
 acetate. ''ihis precipitated lead arsenateand the whole 
 
 mixture was then poured into the spray tank for the use. 
 
 IhlTI^J. IhbaCflClhli IhLUbfRY. 
 
 The first successful commercial manufacture was 
 carried out by Gornelius h. Yreeland of iviontelair, h. J. 
 
 In February, ±906, he made application lor a patent covering 
 an electrolytic method of preparing ar- enic compound of lead, 
 U. 0. 870, 9i£ (1906) 
 
 for s veral years his " hlectro " brand manufactured in a 
 little plant in I'otowa just outside of rat ter son, i. . J. was 
 the be. t known in the market. I'he process was , how- 
 ever, abondoned by his firm. ■ 
 
 rhe method of precipitation of lead arsenate 
 by sodium arsenate and lead acetate, wlilch wasv then being 
 by several small x^lants, was expensive. ^irsenic 
 
 acid and litharge are fairly cheap raw materials, 
 iixtensive experiment on the use of the said compounds start- 
 
-7- 
 
 ecland _inally came out as a commercial product. 
 
 Cliom. Let. ■^ng.__24, I19k<lj 1. o<ol. 
 
 ±n 1909, K.-O. ^uther and . K • Volck, of Watsonville, 
 California, obtained a patent on tke manuiacture oi lead 
 arsenate by mixing arsenic aci5. and litliarge. 
 u. b» 9f9,96E, iiug . o, 1909. 
 
 'ilie mixture was roasted in presece of oxygen assitted by 
 oxydizing agent. -^-ead arsenite , formed at tke 
 
 eary stageb, is oxydized into arsenate. ^ince that 
 
 time more than a dozen patents are taken out 'on the supject. 
 
 xi.pprox;imat e chemical composition of commercial aisencute. 
 
 Thre rae several kinds or laed arsenate possible. 
 
 'i'he original product was vhat is knoir.n as a Griplumoic 
 arsenate of lead, O 4 
 
 theoretically it contains 
 
 74 . 4 E percent of xb 0 . 
 
 E5.58 " ” 
 
 and the other is orthoplumbic arsenate, v;hich contains 
 theoretically 
 
 64. S8 percent 
 
 of 
 
 xb 0 
 
 55.13 
 
 
 £.59 
 
 ” K ;,0 
 
 -4m. bhem. 80 c. 
 
 11915) 
 
 X. 1685. 
 
•- a 
 
 
 
- 8 - 
 
 
 commercial lead arsenate is a mixture oi the above 
 tv.o forms in different propoi-tions ,and this variatipn in the 
 proportion due to the different methods of preparations, 
 file value of the insecticide is determined by the amount of 
 arsenic in the compound; and some of the best grade contains 
 up to 50 per cent of arsenic oxide. 
 
 By the Insecticide and Fungicide Act of 1910, the 
 paste form of lead arsenate should not contain more than 
 50 percent of vvater. rt should contain at least 12 l/2 
 
 per cent of arsenic oxide, and less than s/4 of one percent 
 of arsenic oxide in water soluble form. 
 
 Chem. Age, (1951^ no. 7, p. 257 . 
 
 'I! fxOCxJOS 01' flilv Oi ACT Ui till CF ABr i'.Aji iXi-J.— >1A1 ju > 
 
 fhe larger part, probablymore than three fourths 
 of the arsenate of lead .produced in this country, is made 
 by the interaction of arsenic acid and litharge. 
 
 'i'herej are t’v^o distict methods of manufacturing • - 
 one being a 'wet process and the other , 'which is rather 
 a recent invention, being dry method, 
 fry methods'. - 
 
 8. 2: 1,544,055 I 1920 j by 1. Eedenburg 
 and f* 2* fx’att . 
 
 b. 2. 1,17 5,565 by n. 2hepherd, 1 1916 J 
 
-9- 
 
 ind. and o^ng. Chern. lb, (19211 p. 551. 
 ilie ra\7 materials commonly used , due to the cheapness 
 are litharge and white arsenic. wome processes, howerver, 
 claim certain advantages in using lead nitrate , white lead, 
 lead peroxide, and lead acetate. 
 
 Current Quotations on rrices of haw Ivlaterials Used. 
 
 by carlot less carlot 
 
 nitharge per lb. 0.07 I/2--.O8 .081/e--.09 
 
 ■.ihite arsenic " . O6---.06I/4 .06 1/e--.o7 
 
 nead nitrate ” . .15 .20 
 
 ^ead acetate " .10 5/8--. 12 1^ 
 
 head arL^enate i paste .09--. 09 1/2 .010 .0.11 
 
 i^ead arsenate ” .06 l/ 2 .o7 .07 1/2-.O6 
 
 I in powder/ 
 
 uodium nitrate" .025 .026 
 
 Ohem. het . -^^ng. Oiiipt. 1921. 
 
 •jodium arsenate per lb. 0.76 
 
 Quoted from price li^t of Hillinckrodt Ohem- 
 
 ical .-orks Q921i 
 
 8odium arsen'ate 0« 1. per lb, yO.52 
 j. B.hake:^ Chemical company. 
 
- 10 - 
 
 '•'lii \ 
 
 ^ij'ps.ratus u>: ed , - 
 
 iinipmeter-- west on direct reading: ampmeter, hi'.vinp 
 rea0-in£, ox x«3 a*-*piiieterx’ • 
 ivheos tat --(Carbon rheostt-t. 
 
 Toltmeter-rreston direct cu.rrent voltmeter having 
 5 ang 10 volts oi reading. 
 
 ^l;.ctrodes used--v-arbon , iron, lead, ana copper. 
 
 Cell iar-- One liter beaker is used. 
 
 -diaphragm-- porous porcelain cup. 
 
 iource OI electricity — xrorn 110 volt direct current, 
 kiagreim of a,H;'aratus . 
 
- 11 - 
 
 i~*iA -L Hl XIkjJ *1^] 1 1* 
 
 Ihe first epperiment based upon the theory of preci- 
 pitation of insvoluble lead arsenate in contact with arsenate 
 ion from soluble arc-encite salts with lead ion electrolytically 
 set free from the lead anode. i‘he commonly known salts 
 
 such as sodium arsenate and sodium biarsenate are.; tried. 
 
 ihe different kinds and different concentrations of 
 electrolytes, various electrodes, and the effects upon the 
 precipitation with various curi'ent densities were tested. 
 
 ihe following experiments were performed under 
 fixed conditions only varying the electrolyte and its con- 
 centrations. 
 
 Ihe fixed conditions are 
 
 klect :|iodes , -*-^athode , - Cu rlate whose area 
 being l.V dm. sq. 
 i:..node , --xb . plate v;hose area being 
 2.6 dm . s q . 
 
 Current density,- 0.5 amp. per sq. dm. 
 ■temperature,- -o.t room temperature. 
 
 Duration of run,- 30 minutes, 
 
 Ei.periment 1. 
 
 rllectrode used ,- sodium biarsenate. 
 
 Concentration,- 5 per cent solution. 
 
 Observation, - 
 
 ■uydrogen gas from the cathode, 
 uxygen from the anode. 
 
- 12 - 
 
 iio precipitate Vvas obtained. 
 
 i!it;periinent 2. 
 
 Electrode used,- Sodium arsenate. 
 
 Concentration,- 5 per cent solution, 
 observation ,- 
 
 evolution oi tlie gases as in the preceding exp. 
 ho precipitation was obtained. 
 
 Experiment 3. 
 
 Eliectrolyte used,- Codium biarsenate, 
 ooncentration, - 10 per cent solution, 
 
 observation. - 
 
 oame as the precedings. 
 
 -experiment 4. 
 
 -electrolyte used,- oodium arsenate, 
 ooncentration, - 10 per cent solution, 
 observation,- oame as the precedings. 
 
 ihe affect of secondary *jalts. 
 
 'fhe effect of the presence of secondary salt in iiie 
 electrolyte was tested, as it was suggested by o* i'. Carrier. 
 He succesfully used sodium chlorate or sodium acetate in 
 the preparation of white lead from sodium carbonate solution 
 with lead anode. 
 
 ■J. -^'hys . ohem. ^1909; 3^, -i-p.256 and 3o2. 
 
-13- 
 
 -LTans. -L:^lectro. '-^hem.uoc. il904; p. 229, 
 
 u, S.644, 779 ly xacliard and iloepper. 
 
 iixperrment 5. 
 
 ^'’lectrolyte used,- 
 
 50 parts oi' 5 per cent of sodiua arsenate 
 50 " '• ” " ” " sodium chlorate 
 
 ubservation, - 
 
 Oases from the both electrodes, 
 ho sign of precipitation. 
 
 Experiment 6. 
 
 xilectrolyte used,- 
 
 50 parts of 5 per cent ol sodium acetate. 
 50 2 " " ■' souium arsenate 
 
 ubservation, - 
 
 ^ame as the preceding. 
 
 ifeperiment 7 , 
 
 electrolyte used,- 
 
 20 parts of 5 per cent o_ sodium arsenate 
 40 ■■ " " “ ” sodium acetate. 
 
 40 " " " " sodium chlorate. 
 
 Observation, - 
 
 eame as the preceding. 
 
-14- 
 
 Summary 
 
 ox experiment 
 
 e-eries 
 
 1. 
 
 
 exp . 
 
 Electrolyte 
 
 , eoneent. 
 
 ulservation. Precipitation. 
 
 1 
 
 x^ia^ n As 
 
 5/0 
 
 sol. 
 
 uases evolut . no. 
 
 from electrodes. 
 
 2. 
 
 i'ia^-ii-s 0^ 
 
 5 7^ 
 
 sol . 
 
 «( 
 
 2. 
 
 na^A asu^ 
 
 10 70 
 
 sol . 
 
 ( < > * 
 
 4. 
 
 i^a^As 
 
 10 7^ 
 
 sol . 
 
 II )• 
 
 5. 
 
 ^ parts of ix 
 
 a^-^s 
 
 5 70. 
 
 
 50 *■ " l^a.^1 5 /o. 
 
 6. 50 parts of i^aAs 5 7*?. 
 
 50 ~ " i^a COUCH 5 'jo 
 
 7. 20 pts. of iiaa^is L-v 
 
 40 ■' “ Ka oOuCH 
 
 40 " '■ -tia CLO3 
 
-15- 
 
 I'he conditions being the same, the effect on 
 various concentrations of electrolyte -was tested. 
 
 rsperiment 1. 
 
 i:ilectrolyte , -500 CG. Of 1 )o of ha^Agi^ .^ol. 
 observation, - 
 
 ihe gases from the both electrodes, 
 no precipitation. 
 
 iiixperiment 2. 
 
 --fter 15 minutes of electrolysis of the experiment 
 1,5 grams of sodium arsenate is added. 
 
 j-he observation and the results are the same. 
 
 experiment 5. 
 
 nfter 15 minutes of electrolysis of experioient 2, 
 
 5 grams of sodium arsenate is added. 
 
 observation,- Ko precipitation, but slightlty 
 cloudy. 
 
 Experiment 4. 
 
 Ihe filtrate of the experiment ef 2 is electrolyzed 
 for 15 minutes after addition of 5 grams of sodium arse- 
 nate , 
 
 ob.. ervation, - Became very much cloudy. 
 
 .•«eight of the precipitate obtained 0.1042 gm. 
 

-16- 
 
 ikperinaent 5. 
 
 ^ftei" 15 minutes of electrolysis of experiment ’ 4, 
 filtered. i'o filtrare 5 grams of sodium arsenate is 
 
 added, and electrolyzed. 
 
 ubservation, - i^o precipitation. 
 
 Experiment 6 . ^ 
 
 After 15 minutes of electrolysis, 10 grams of 
 sodium arsenate is added. 
 
 Eo precipitation. 
 
 / 
 
 jSxperiment 7 . 
 
 After 15 minutes of electrolysis, 15 grams of 
 sodium arsenate is added. 
 
 bo changes from the preceding experiment 
 observed. ^ 
 
 Summary for the experiment series 2. 
 
 ■fhe small amount of precipitation vv^as obtained in 
 experiment 3 and 4, vvhose concentrations are 3 and 4 respeclr 
 ively . 
 
-17- 
 
 1 bEi\Ixj3 3, 
 
 The effect of the varying proportion and the 
 concentrations of the electrolyte and of the secondary 
 salts is determined. 
 
 The fixed conditions are the same with series 
 1 experiment. 
 
 The quantity of electrolyte taken in each exp- 
 eriment is 500 CC. 
 
 The electrolyte was kept in acidic codition 
 with nitric acid and indicator, in order to prevent 
 the formation of basic lead salt. 
 
 iiir is bubbled through the electrolyte in 
 order to stir the precipitates formed. 
 
 Experiment 1. 
 
 electrolyte,- 2pts of S of sodium arsenate. 
 
 3 “ "5 " ” pottasium chlorate. 
 
 observation, - 
 
 Voltage drop, -5.0 v. initial, o,S v. final, 
 hydrogen gas from the cathode and precipitat 
 cling to the anode. 
 
 .weight of precipitate obtained after 30 
 minutes of run, 2.3830 gm. 
 
 experiment 2. 
 
 Electrolyte,- 2 pts. of of sodium arsenate. 
 
 3 " “5 /u " pottasium chlor- 
 
• ■ o' .' -'*■' f ' .*‘ -, .:• ’ ^ ‘jI > ^ 5 ^' *' ■' 
 
 V-*’*' O’ TjJk'- ow^hmK. 
 
 
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 >• r*" »■ 
 
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 ■ A. 
 
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 ► J' 
 
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-18- 
 
 ate « 
 
 Voltage drop,- initial ^.8 v. final 5.£ v. 
 Wt . of precipitation obtained, 3.7825 gni. 
 
 j-ixperiment 5. 
 
 i^lectrolyte ,- 2 pts . of 10 )o gol. of sodium arsenate. 
 
 5 ”5 ” ” "-t— clilorate. 
 
 Voltage drop,- initial 4,7 V. final 6.8 v. 
 
 V/eight of precipitation , 2.7 572 gm. 
 
 experiment 4. Ohanging the concentration of n-chlorate. 
 
 Electrolyte, -t 2 pts. of 2>1o^ Of n- chlorate. 
 
 I 3” " ” 5 " " sodium arsenate. 
 
 Voltage drop,- rnitial 7.0 v. final 7.9 y. 
 
 weight of precipitate obtained , 2.0 876 gm. 
 
 Experiment 5. 
 
 Electrolyte,- I 2 pts. of 6 E of n-chlorate. 
 
 I3 ” "5 " " Eodium arsenate. 
 
 initial voltage ^rop, 4.9 y. , final 5.5 y. 
 
 v.eight 0- precipitate obtained, 2,2564 gm. 
 
 Experiment 6, 
 
 Electrolyte,- I 2 pts. of 10 Of h- chlorate. 
 
 15 •’ ” 5 > " sodium arsenate. 
 
 Initial voltage drop 4.9 v., final 5.5 v. 
 
 i/eight of precipitate obtained 2,3605 gm. 
 
-19- 
 
 iiixperiment 7. increasing amount oi i^- clilorcite. 
 
 illectrolyte , - 1 Spts. oi 10 'jo of chr orate. 
 
 (2 " ” 5 ” sodium arsenate. 
 
 Voltage drop, initial 8.2 v. , final 8.6 v. 
 
 ./ei^ht of precipitation obtained 5. 6542 gm. 
 
 i^xperiment 8 . 
 
 -Electrolyte t 4 pts. or 10 of -S- -clilorate sol. 
 
 I 1 " “ 5 '■ " sodium arsenate. 
 
 voltage drop,- initial 2.6 v. , linal «i>.6 v. 
 
 ..eight of precipitate 1.5582 gm. 
 
 
 EULlIAxvY pa. 
 
 . IKE 
 
 EAPEi.ILIElvi' 
 
 s El k 1 iii kj if 3 
 
 • 
 
 
 iJxp. 
 
 hlectro- Oonc. 
 lyte . 
 
 Eroport . 
 
 Voltage 
 init . 
 
 drop, 
 linal. ' 
 
 5t . of ppt. 
 
 1 . 
 
 1 Ua^AsO^ 
 ( h CIO 3 
 
 "d^/o 
 5 “ 
 
 2 pts. 
 5 " 
 
 5.0 
 
 6 .3 
 
 2.3820 gm 
 
 2 . 
 
 1 lias -^s 
 (h C 1 O 3 
 
 6 
 
 5 
 
 2 n Ets . 
 5 
 
 3.8 
 
 5.2 
 
 5.7825 " 
 
 5 . 
 
 ( i'ia 3 .‘.^s • 0 ^ 
 ( n 010 ^ 
 
 10 
 5 '■ 
 
 Cj p>t S . 
 
 4.7 
 
 5.8 
 
 2.7572 " 
 
 4. 
 
 1 JiCl L| 
 (lJa 3 As 
 
 5 /J 
 
 5 •' 
 
 2 " 
 
 5 ■■ 
 
 7.0 
 
 7.9 
 
 2.0876 " 
 
 5. 
 
 [ X- 01. 3 
 
 6 >0 
 5 " 
 
 2 pts 
 5 
 
 . 4.7 
 
 5.9 
 
 2.2564 
 
 6 . 
 
 1 ir 01 C 3 
 (hajAso^ 
 
 lo P 
 5 " 
 
 2 pts . 
 
 rr 1 - 
 
 0 
 
 4.9 
 
 5 . 5 
 
 2.3605 
 
 7 . 
 
 1 A Cl O 3 
 (IIe^xsO^ 
 
 lo 
 
 5 " 
 
 3 i>ts 
 2 " 
 
 . 8.2 
 
 8.6 
 
 3.6542 
 
 8 . 
 
 IACIO 3 
 
 10 '^ 0 
 
 4 pts 
 
 2.6 
 
 5. 6 
 
 1.3382 
 
- 20 - 
 
 ■i U/ i ^ jCi-fc X b X j-j 
 
 ■■i.’'he e:^Lperiment Vvc s done , using th.e method of 
 Vreeland's patent. 
 
 870,915 I 1908J 
 
 he u. ed a cathode of iron in a solution of alkaline 
 hydrozide contained ij. a porou.s receptacle, uhich in turn 
 vv-as placed ir a vessel containing an anode of lead and a 
 solution of a salt v;hieh v;hen electrolyzed vill produce a 
 soluble lead salt. ^-ead aricenate is formed by means of 
 
 a soluble s.ult o: arsenic. 
 
 fhe reactions involves iij the; reactions are 
 
 x-a"^ goes into the cathode__ ^ i.a + 0 
 
 i-a reacts with the water — yh^-t '-h 
 
 -b x.Oj by electrolysis — ^ ^^b'^ + 1 X 3 
 fo the above solution sodium ^ rsen- te ie added, 
 i'b IhOj s " . 
 
 fliio sodium t.nd nitrate are again used as anode 
 solution in the next operation. rhis xrocess , therefore , 
 
 is simply the electrolytic p eduction of lead nitrate. 
 
 fhe conditions fixed for the ■■•xporiaient are 
 
 -electrolyte , -rahO in anode and in eatiiodc 
 
 comT'^c^rtments . 
 
 Concentration,- 5 per cent solution of ei^cli. 
 -.lectrodes , - 1 ^-node,- o-o;.. d plate who-o area 
 
 { L.'vj Sg. 
 
 I 
 
 (cathode,- xron bar .■vhose area 1.7 
 
 ar.i . 
 
j • J. "V f ^ 
 
 
 V 4 / ^ , V • ‘ • /■ f ’ • A ' <■ 1 • ^ iBii 
 
 V J. ' '’ M-, , •* M ^ • ' • ' ■■ 4 " 
 
 ^ 4 ■# . ■ V ‘ ^ -tv* . >■ 'l^-' 
 
 ,' ^ •' , •;?, *v^ lU '> ^' ■ .Vf'i *^ii • ‘ IfjUl 
 
 ■S.' I 
 
 T *' i' 
 
 k. 
 
 
 ii.)*; : 1 , -f.i ff. .Ji ■ I . ■• 
 
 * ' ‘ • ». ■*/? !<« jk-' ■l>- fV.Vr 4 ^, 
 
 ■ . , .' : 1. !v:< V,i ’'■' ' ’’. ® V ‘'' ? 
 
 ■' ■ ; *.^ ..•/"•■'WdEl/’J iS’i • 
 
 *<i* •. / I'/A’ ** -'i^. r '■' ’i? -' '^SoPfedli 
 
 
 
 
 . 
 
 ■ *'. I "''»l,<f '. .'> li ^ -' J/ ' ^ Y *•* •■ •>j-’i'l| f'** |k' P ''#4^ **■! * '^Pl- 
 
 • V. . ' u > . . . - li.i. A- *-( ■ A I - •?' /!**^*^' 7 ,’ 
 
 ' 4( M ;,' ..'Sg 
 
 ^ « 'mC 'y' ’' t~ ' -,’ vaSI'V '■■‘.'.V V?t»' ’"' '■ .'if f.'i^ ■‘'i .'V 
 
 
 •: :MfX. yii» y' -*fJ9K4 '.■j!* 
 
 , . ■?' 'jti 1 , i ' ' !f . ( . * 1 '. , < 4 ' 
 
 
 
 
 Vtl 
 
- 21 - 
 
 Liurrent o.eiisity,- 0.5ci. amp, per sq. dm. 
 
 Duration oi run,- 30 minutes, 
 rafter tlie i-un in each experiment, 10 percent solution 
 of sodium arsenate is added until! the solution is salsurated 
 and teh solution is filtered, the precipitate then dried 
 and weighed. 
 
 iiixperiment 1. 
 
 500 Of 5 percent of sodium nitrate solution is 
 taken • 
 
 .^eig,ht of the precipitate obtained--? .3167' gm. 
 i^pE riment 2. ' 
 
 'fhe filtrate from the experiment 1 is again electro- 
 lyzed for 30 minutes , and saturated with sodium arsenate, 
 the precipitate Vvas filtered and neighed. 
 
 uei, ht of ppt.-- 10. 176 5 gm. 
 
 « 
 
 Experiment 3. 
 
 ■ihe filtrate of experiment 2is electrolysed, and 
 the precipitatev;as w-eighed. 
 
 weight of precipitate — 10.6382 gm. 
 
 Th.e process goes indefinitely by addition of 
 sodium arsenate, the weights of precipitate obtained aie 
 7.2167 gm. , 10.1765 gm., and 10.6382 gm.respec tively . 
 
ju iiiXt -L ^ j-j - fc Xi-* 5 • 
 
 I'he effect o^. various catliodes vas examined, 
 file fixed c ond i t i ons a r e 
 
 Electrolyte,- 5 per cent of sodium arsenate, 
 current density, -0.5 amp. sg. dm. 
 l>urration of run,- 20 minutes. 
 
 Ex p e r imen t 1 . 
 
 nlectrode used,- lEad catliode liaving area of 2.3 sq. dm. 
 Voltage drop,- initial 6.8 v., final 6.4 v. 
 
 ./eiglit of precipitate,- 1.8226 gm. 
 
 Experiment 2. 
 
 x^lectrode, - Liarbon -whose solution area o.74 sq. dm. 
 Electrode portential,- initial 9,0 , final 8.6 v. 
 
 ..eight of precipitate,- 4.Y858 gm. 
 
 Experiment 5. 
 
 electrolyte,- copper plate vdiose area 1.7 sq. dm. 
 electrode portential,- initial 9.0, final 8,6 v. 
 weight of precipitate,- 5.0'. 42 gm. 
 
 Experiment 4. 
 
 Electrode,- iron rod nhOoe.. electrode area being 
 0.7 sq. dm. 
 
 Electrode portential,- initial 12.0 v. rinal 10,8 v. 
 
./eight of precipitate obtained,- 1.5350 gm. 
 
 u]? ' 5. 
 
 Carbon electrode gave the best yield and copi-er also 
 hi fx value under the given condition. iron and lead 
 gave very lov value. 
 
1. ii^luenceB of different el^-ctrodes for the pre- 
 
 cipitation. 
 
 und( rthe same condition, b y changing electrode, 
 variable precipitate was obtainedas sho..n in the er^eii- 
 ment series 6. 
 
 2. i^iffect of change concentration in the electrolyte. 
 
 There is an optinum concentration for the precip- 
 tation under each condition. The conditions may in-, 
 
 elude current density, various cathodes, nature of electroly 
 tempreture of the bath and Some others. 
 
 onder the condition o experiment series 2, the 
 conc' ntration of S or 4 percent was found as the best 
 suited. 
 
 5. rnfluence of the secondary salts. 
 
 As to the possible explanation of the. function of 
 secondary salt presented, 
 
 a. ihe presence of the secondary salt increases 
 
 the conductivity of theelectr olyte . 
 
 D . 
 
 ■fliis in turn acceleratesthe speed of lead 
 
 going into the ionic form. 
 
 c. 'The ionized lead will o^uickly take up arsenate 
 
 ion forming insoluble lead arsenate. 
 
 3 
 
-25- 
 
 d. This conseauently increases the dissociation 
 of .:odiiiai arsenate used. 
 
 e. As inference, the secondary salt, therefore, 
 should be highly ionisable salts. 
 
 4. The use of soluble salts of arsenate. 
 
 ns industrial process the use of soluble salts 
 of arsenate is seems to me impossible, owing to the high 
 cost of arsenate salt. i5y this very reason Vreeland, the 
 
 inventor of electrolysis method, has abondoned his proerss 
 as soon as the other process, which use cheaper ravv material 
 for the manufacture of lead arsenate .came into enistence. 
 
 As ascientific investigatio n this is an interesting 
 subject. The sturdy may lead to establish some theories 
 
 which may be applicable to similar reactions. 
 
 The use of cheaper raw materials, such as white arse- 
 
 t 
 
 nic , litharge, minium, or galena is essential .or the develo 
 merit of lead arsenate industry.- from this standpoint, 
 
 it may be well to investigate on electrolysis of fused white 
 ar; enic and lead salts. ur it may be advantagious to 
 
 pass electric current through mf?:ed vapor phases, as these 
 arsenic and lead salts are easily sublimed at a fairly 
 
 low temperature